The disclosure relates generally to ceramic precursor batch compositions and more particularly to ceramic precursor batch compositions and batches for forming ceramic honeycombs.
In the formation of ceramic bodies, e.g., silicon carbide, cordierite, mullite, alumina, or aluminum titanate bodies, plasticized mixtures of various inorganic powder batches are prepared which are then formed into various shapes. These plasticized mixtures should be well blended and homogeneous in order for the resulting shaped body to have relatively good integrity in both size and shape, and uniform physical properties. These mixtures typically further include organic additives such as binders, plasticizers, surfactants, lubricants, and dispersants as processing aids to enhance cohesion, plasticity, lubricity, and/or wetting, and therefore to produce a more uniform batch.
Cellulose ethers have been used as extrusion binders to impart plasticity while imparting good drying behavior. While other ceramic binder systems can also be used for ceramic extrusion, cellulose ethers such as methylcellulose (MC), hydroxypropylcellulose (HPMC) and hydroxyethylmethylcellulose (HEMC) can form high temperature gels. The gelling behavior facilitates rapid drying while preventing distortions that can occur with other binder systems as they are heated.
In order to form the batches described above into various shapes, the batch materials are usually fed through an extruder. The rate at which the batch materials can be fed through the extruder is limited in part by the Tonset of the batch. Tonset refers to the temperature at which the rheology of the batch begins to transition from low to high viscosity. Higher Tonset can enable greater batch feed rate and higher batch feed rate can result in reduced processing costs.